Lynette has a bionic arm (a deliberate Bionic Commando reference) and glasses. She is secretly sleeping with Todd Ingram behind Envy's back.
In Scott Pilgrim vs. The World: The Game, she functions as a double mini-boss with Envy. Lynette's teleportation and telescoping bionic arm are her chief powers. Once the duo are defeated, they brawl amongst themselves for a bit before Lynette teleports away, leaving her arm behind, which explodes into money.
In the Scott Pilgrim film, Lynette's role is greatly reduced from both the comic and the game. She only drums during "Black Sheep" and stands around backstage. Her most significant action, punching the highlights out of Knives' hair, is given to Todd instead.
Lynette's last name comes from Tom Guycott, the antagonist of her band's namesake.